Non-insulin-dependent diabetes mellitus (NIDDM) has been shown to have a large interpopulation variation that is believed attributable to environmental difference. Cumulative research evidence suggests a close relationship between dietary factors, obesity, body fat distribution and the risk of NIDDM. Rich information from a diabetes prevalence survey (data collected in 1995 on 40,000 subjects) and from a longitudinal study of 1500 individuals surveyed in both 1989 and 1993 will provide a unique opportunity for studying diet in relation to NIDDM risk. The dietary pattern of the Chinese people is shifting rapidly from a low fat, low protein diet to a diet more typical of the Western pattern, with increasing consumption of animal foods and saturated fat. The proposed study will primarily investigate the role of dietary factors, including sources of fat and type of carbohydrate, in the development of impaired glucose tolerance (IGT) and NIDDM. Secondly, the relation of body adiposity and body fat distribution to diabetes risk will be investigated. A unique feature of this population is the high levels of physical activity and low levels of obesity. In this context, we will be able to investigate the role of dietary factors independent of obesity thus allowing a better understanding of the direct and indirect effect of dietary factors than would be possible in a Western population where the prevalence of obesity is much higher.